Add the -ffixed-r9 for ARM as workaround for the lack of -ffixed
Add gcc ARM flags -munaligned-access / -mno-unaligned-access

clang already had a mstrict-align which mentiones "Force all memory
accesses to be aligned (ARM only)". On gcc arm this is controlled by
-munaligned-access / -mno-unaligned-access. Add the gcc versions to
the frontend and make -mstrict-align and alias to -mno-unaligned-access
and only show it in clang -cc1 -help.

Since the default value for unaligned accesses / strict alignment
depends on the tripple, both the enable and disable flags are added.
If both are set, the no-unaligned-access is used.

The options are added to the newly created m_arm_Feature_Group.
The option marm / mno-thumb are also placed into that group.
update -arm-darwin-use-movt=0 -arm-use-movt=0 in accordance with llvm